This invention generally relates to a hinge.
More specifically, the present invention relates to a hinge having the functions of (1) providing a specified braking force in pivot unfolding or folding of two flaps by which, when the flaps are pivotally folded or unfolded to a specified angle or are folded over each other, xe2x80x9cclickxe2x80x9d to a stop of their pivotal motion, and (2) allowing for application of a specified force in the direction of pivotal motion to release the flaps from their xe2x80x9cclickedxe2x80x9d state. Such a hinge may be used for connecting together a transmitter-side casing and a receiver-side casing of a folding portable mobile telephone, for example.
A portable mobile telephone as shown in FIG. 14 is disclosed in Japanese Patent Laid-open No. 11-68901, and a hinge as shown in FIG. 15 is used for this portable mobile telephone. The portable mobile telephone shown in FIG. 14 is composed of a transmitter-side casing 50 having a transmitter part 51 and operation keys 52 and a receiver-side casing 60 having a receiver part 61, a display part 62 and an antenna 63. The casings 50 and 60 are connected together through a pair of hinges 7, 7.
Each hinge 7 has axially aligned cylindrical conductive bearing parts 70, 71, and one bearing part 70 is connected to the transmitter-side casing 50, while the other bearing part 71 is connected to the receiver-side casing 60. Reference numeral 73 denotes a connector cover.
A ring-like friction-bearing member 72 made of metal is fixed to the inside of the bearing part 71, as shown in FIG. 15. This friction-bearing member 72 is in contact with an end of a cylindrical friction member 73 made of metal and mounted in the bearing part 70.
A shaft 74 has a flanged spring seat 74a, also serving as a cover, at its base end and a bolt part 74b extending therefrom through the bearing parts 70, 71. A spring 75 bears against the base end of the shaft 74. The spring 75 is compressed by tightening the bolt part 74b of the shaft 74 with a nut 76 which extends through an open end of the other bearing part 71 to press the friction member 73 against the friction-bearing member 72 for braking.
Reference numeral 77 denotes a cylindrical flat spring also serving as a spring seat. The tip end of the flat spring 77 is in slidable contact with the outer surface of the friction member 73 and with the inner surface of the bearing part 70, providing conduction of frame grounding in the casing.
In the above-described hinge, the friction-bearing member 72 and the friction member 73 are held in surface contact with each other under a specified pressure by the action of the spring 75. Thus, the casing 60, when folded over or unfolded from the casing 50, is braked by a specified force through friction between the friction-bearing member 72 and the friction member 73.
Further, the sliding surfaces of the friction-bearing member 72 and the friction member 73 have parts with tapered surfaces at positions spaced at an interval of a specified angle (160 to 180 degrees). Thus, when the casings 50, 60 are pivoted open to a specified angle, the tapered parts engage with each other for locking or xe2x80x9cclickingxe2x80x9d the casings. Forcing the casing 50 pivotally relative to the casing 60 releases the casings from their xe2x80x9cclicked statexe2x80x9d for folding the casings over each other (closed). Then, the tapered parts again become engaged with each other when the casings are folded closed.
Since the hinge in the above prior art utilizes the pressure of the spring 75 in the axial direction, the contact between the friction-bearing member 72 and the friction member 73 in the turning direction is structurally limited to a short length, resulting in the need for a larger-sized spring to provide sufficient braking force against pivotal motion. However, since the bearing 70 has an outer diameter of 7 mm or less in most cases, a large-sized spring can not be used for the above hinge.
Although an increased number of springs is supposed to meet a demand for higher braking force, the structure of the above hinge does not allow for mounting a plurality of springs (two springs, for instance).
Accordingly, it is an object of the present invention to provide a hinge, which utilizes the pressure of a spring in the direction of pivotal motion of the flaps more efficiently by increasing the contact length of frictional parts.
A hinge according to the present invention comprises a bearing body, which has, at its exterior, mounting parts for a first flap and a wear-resistant inner surface having slider holding parts (xe2x80x9ccatchesxe2x80x9d) at positions spaced at an interval of a specified angle on the same circumference. A shaft has, at its one end, mounting parts for a second flap, and is inserted into the bearing body in a manner allowing relative turning. The shaft also has a spring housing hole opening at one end at the shaft""s outer surface so as to cross at right angles with a longitudinal axis. A coil spring is inserted into the spring housing hole and a slider is biased by the coil spring so as to be pressed against the inner surface of the bearing body. The slider has wear-resistance at least at its tip end which contacts with the inner surface of the bearing body, and is capable of engagement with and disengagement from the slider holding part (slider catch) when the bearing body is turned relative to the shaft.
The slider may have a spring guide pin for mounting the coil spring externally fitted to the guide pin. Optionally, the slider may be in the form of a hard ball or a hard roller having its axis parallel to an axis of the shaft.
In a preferred embodiment the slider has a semicircular section orthogonal to the axis of the tip end making contact with the inner surface of the bearing body, and makes contact with the inner surface portions of the bearing body, other than the slider catches continuously over a specified axial length.
The surface portions of the slider in contact with the coil spring are preferably planar.
In a preferred embodiment, the slider holding part or catch is in the form of a hole.
A plurality of paired slider catches may be located in the same circumferential location, and a plurality of spring housing holes axially paired so as to face corresponding slider catches, and with coil spring and a slider housed in each spring housing hole.
The slider catch may be formed in the shape of an axial groove on the inner surface of the bearing body and may have a concave semicircular section.
Where the slider holding part is formed as a groove having a concave semicircular section, with a plurality of spring housing holes axially aligned so as to face in the same circumferential direction and a coil spring housed in each spring housing hole, the slider should have an axial length extending across the spring housing holes, and the spring housing holes are recessed to such an extent that the tip end of the slider is hidden when in contact with a part of the bearing body other than a slider catch.
The bearing body may be composed of a synthetic resin body and a metal interior sheet fixed to the inner surface of the resin body.
A transmitter-side casing of a portable mobile telephone may be attached to one of the first and second flaps, while a receiver-side casing of the portable mobile telephone is attached to the other, in which application the bearing body and the shaft should have conductivity.